Pushbutton switch with actuator adjustable by interference fit

ABSTRACT

An electrical switch comprising three members, the first and second of which are relatively movable against a biassing force to make and/or break an electrical circuit. The third member is an interference fit within a bore formed in one of the other members and constitutes an adjustable extension thereof, and in turn forms an abutment whereby the switch is operable. The electrical switch in accordance with the present invention finds particular application as a courtesy light switch in automobiles, refrigerators, etc.

United States Patent [191 Palman [451 Oct. 23, 1973 PUSHBUTTON SWITCH WITH ACTUATOR ADJUSTABLE BY INTERFERENCE FIT Primary Examiner-Robert K. Schaefer [76] Inventor: Leonard Palman, 5 Windsor Close, 33 i g g g g g Vanderhye Hendon Ln., London, England omey o n c or [22] Filed: Dec. 13, 1971 57 ABSTRACT [21] Appl. No.: 207,296 An electrical switch comprising three members, the first and second of which are relatively movable [52] Us. CL 200/159 R against a biassing force to make and/or break an elec- [51] Int Cl 13/52 trical circuit. The third member is an interference fit [58] Field R 61 89 within a bore formed in one of the other members and constitutes an adjustable extension thereof, and in [56] References Cited turn forms an abutment whereby the switch is opera- U E STA E ble. The electrical switch in accordance with the pres- S PATENTS ent invention finds particular application as a courtesy 2,921,155 1/1960 Basso 200/159 R X li ht switch in automobiles, refrigerators, etc. 3,432,634 3/1969 Basso 200/159 R 1 3,251,971 5/1966 Fraser 200/159 R 2 Claims, 3 Drawing Figures 7 i i F 1% I I L' 1 6 I I l I l l l 1 4 l 5 7a 461 v "A a PAIENIEnnm 2 3 I975 SHEET 1 [IF 2 PATENIEUncrzs ms 7 7 877 swam 2 BF 2 PUSIIBUTTON SWITCH WITH ACTUATOR ADJUSTABLE BY INTERFERENCE FIT This invention relates to an electrical switch and more particularly to an electrical switch suitable for use in connection with courtesy lights in automobiles, boot lights, refrigerator lights and similar applications.

According to this invention an electrical switch comprises three members of which the first and second are relatively movable against a biassing force to make and/or break an electric circuit and the third of which is an interference fit within a bore formed in the said first or second member to form an adjustable extension thereof and to form an abutment whereby the switch is operable. Preferably the second member is made from a resilient and deformable material and the borethereof is tapered to afford a progressive interference fit with the third member.

Alternatively the bore in the second member may be parallel-sided and the third member frusto-conical in shape. If desired, the bore may be cylindrical and the third member may be of square or other polygonal section to create the required interference fit with the second member.

A switch according to the invention may be used in automobiles employing a negative earth return circuit and in such a case the first member constitutes a housing made from an electrically conducting material and the second member is made from an insulating material, for example a plastics material, and carries a terminal connector. The terminal connector may be retained on the second member by a circlip disposed concentrically with the bore of the second member. The circlip assists in the interference fit between the second and third members in that it possesses a natural tendency to restrict the bore against deformation. Limitation of relative movement between the first and second members may be accomplished by the terminal connector or alternatively a flange or other abutment may be carried by the second member.

The biassing force between the first and second members may be provided by a spring of helical or strip form. However, other forms of spring or hydraulic biassing may be used.

Where an electrical switch in accordance with the invention is used to make or break an automobile circuit for a courtesy light, or a refrigerator circuit for an interior light, the third member constitutes an abutment which cooperates with a door so that the actions of opening and closing the door respectively make and break the circuit. One benefit of the switch in accordance with the invention is that the third member may have any reasonable length and during assembly this member is inserted into the bore of the second member so that the door is closed for the first time, the third member is forced into the bore against the interference fit with the second member by an amount appropriate to the precise position of the door relative to the switch.

Alternatively the relative position of the second and third members may be preadjusted but where one is attempting to save time on an assembly line, the possibility of simply locating the third member in the second member and relying upon closure of the door to produce accurate positioning between the second and third members offers considerable advantages.

Where the space behind a flange in which such a switch is mounted is limited, the terminal connector may be placed in a plane at right angles to the axis of the bore in the second member. In this way the space required behind the switch is very little more than that required to accommodate the relative movement between the first and second members.

One embodiment of the invention, namely an electrical switch suitable for making and breaking an automobile courtesy light negative earth return circuit, will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a side elevation of the switch in the circuitmade or light-on condition;

FIG. 2 is an end elevation of the switch in the direction indicated by the arrow-heads IIII of FIG. 1, and

FIG. 3 is a longitudinal sectional view of the switch in the circuit-broken or light-off condition.

The switch comprises a generally cylindrical, electrically conducting, housing 1 which constitutes the aforesaid first member, a second member constituted by a through-bored insulating sleeve 2 made from a resilient and deformable plastics material, and a third member in the form of a cylindrical rod 3.

The housing 1 is substantially wholly accommodated within, and is secured to, a cylindrical portion of a casing 4; only. an annular terminal flange la, formed integrally with the main body of the housing I at the inner end thereof, protrudes beyond the casing 4. At its outer end the casing is formed with a flange 4a which is apertured at 4b so that the casing 4 (and with it the housing 1) can be secured, as by screwing, to a stationary part of the automobile frame adjacent a door thereof.

The sleeve 2 is longitudinally and rotationally displaceable relative to the housing 1. At its outer end the sleeve is formed with an integral annular flange 2a and this, through its abutment with the outer end of the housing 1, limits longitudinal movement of the sleeve 2 relative to the housing 1 in an inward direction (see FIG. 3). On a reduced diameter part adjacent its inner end the sleeve 2 carries an electrically conducting terminal connector 5, an electrical tab 6 of which is provided with an insulating plastics sheath 7. The connector 5 is retained on the sleeve 2 by a circlip 8 disposed concentrically with the axis of the sleeve. Three peripheral portions 9 of the connector 5 are turned outwardly to form abutments and engagement of these with the terminal flange Ia of the housing 1 limits longitudinal movement of the sleeve 2 relative to the housing 1 in the outward direction (see FIG. 1).

A technical spring 10 accommodated between the terminal flange la of the housing 1 and the flange 2a of the sleeve 2 acts constantly to urge the members 1 and 2 into the position shown in FIG. 1, where the abutments afforded by the outwardly turned portions 9 of the terminal connector 5 engage the flange la to close the switch. 7

The bore in the sleeve 2 is tapered from its outer to its inner end to afford a progressive interference fit with the cylindrical rod 3. As already indicated, this interference is aided by the presence of the circlip 8 inasmuch as the latter resists outward deformation of the sleeve 2 by the rod 3.

During assembly of the switch therod 3 is simply located in the bore of the sleeve 2, without any attempt at accurate positioning. When the switch is secured to a stationary part of the automobile frame adjacent the door, as indicated above, and the door closed for the first time, the rod 3 is forced into the tapered bore,

against the interference fit, by an amount appropriate to the precise position of the door relative to the switch.

At the same time, the pressure exerted on the outer end of the rod 3 by the closing action of the door causes longitudinal displacement of the sleeve 2 relative to the housing 1, such as to break the contact between the abutments at 8 and the flange la. The switch thus assumes its FIG. 3 position, against the action of the spring 10, and remains in that circuit-broken position until opening of the door releases the pressure on the outer end of the rod 3 and permits return of the sleeve 2 to the position shown in FIG. 1 under the biassing influence exerted by the spring 10.

It will be appreciated that relative adjustment be tween the rod 3 and the sleeve 2 occurs only once: namely, when the door is closed for the first time after the switch is fitted. Subsequent opening and closing actions of the door do not affect this adjustment at all. It will be further understood, however; that longitudinal displacement of the sleeve 2 relative to the housing 1 occurs upon each opening or closing of the door, as explained in the immediately preceding paragraph, to make or break the circuit respectively.

What I claim is:

1. An electrical switch, comprising: a first member;

a second member movable relative to the first member; switch means on said first and second members movable into and out of electrical contact with each other, one of said first and second members having a bore therethrough; a switch operating rod-like third member located in the said bore and having an extending end to provide a switch operating outer extension and an inner end; and biasing means for urging said first and second members in said relative movement toward said switch closing position, at least one of the said bore and said third member being tapered throughout substantially the whole of the length thereof to provide a progressive and substantially continuous interference fit between said bore and said third member which, subject to the interference fit, is movable through the bore, thereby determining the location of said switch operating outer extension of said third member relative to said switch means.

2. An electrical switch according to claim 1 wherein the said one of the first and second members that has said bore therethrough is compressible, and there are provided compressing means for compressing the said one member and assisting the interference fit between said bore and said third member. 

1. An electrical switch, comprising: a first member; a second member movable relative to the first member; switch means on said first and second members movable into and out of electrical contact with each other, one of said first and second members having a bore therethrough; a switch operating rod-like third member located in the said bore and having an extending end to provide a switch operating outer extension and an inner end; and biasing means for urging said first and second members in said relative movement toward said switch closing position, at least one of the said bore and said third member being tapered throughout substantially the whole of the length thereof to provide a progressive and substantially continuous interference fit between said bore and said third member which, subject to the interference fit, is movable through the bore, thereby determining the location of said switch operating outer extension of said third member relative to said switch means.
 2. An electrical switch according to claim 1 wherein the said one of the first and second members that has said bore therethrough is compressible, and there are provided compressing means for compressing the said one member and assisting the interference fit between said bore and said third member. 